FIG. 1 illustrates a communications system 100 in which a transmitter (TX) 102 transmits data to a receiver (RX) 104 over a high-speed direct current (DC) serial link 106 via a differential driver 108. As shown, the high-speed DC serial link 106 includes differential lines for conveying differential signals VP and VN to RX 104, and RX 104 includes a differential termination network 110. For a given DC common-mode resistance termination at the RX differential termination network 108, the TX 102 common-mode voltage (VTXCM) can be computed as the average of VP and VN, or (VP+VN)/2. The RX 104 common-mode voltage (VRXCM) 112 generally is the DC voltage value at the termination network 110, and is also referred to as VRXTERM.
Unfortunately, a mismatch between VTXCM and VRXCM may be problematic. For instance, the high-speed DC serial link 106 may incur DC common-mode current (ICM) when VTXCM and VRXCM do not match. The DC common-mode current ICM does not contribute to the differential signaling and, hence, is wasted power. In addition, the additional DC common-mode current ICM requires increased geometry of the wiring of the TX 102 and RX 104 input/output (I/O) to achieve a fixed reliability and/or electro-migration. Larger geometry wiring on the I/O adds parasitic capacitance, which may reduce the bandwidth of the interface. Moreover, the mismatched common-mode voltages VTXCM and VRXCM may result in an increase of common-mode noise due, for example, to mismatched rising and falling edges of the received data signal.